Note: Descriptions are shown in the official language in which they were submitted.
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PLATE HEAT EXCHANGER FOR HEATING OR COOLING BULK SOLIDS
HEAT EXCHANGER FOR BULK SOLIDS HEAT EXCHANGE
FIELD OF THE INVENTION
[0001] The present disclosure relates to heat exchangers for heating
or
cooling bulk solids.
BACKGROUND
[0002] Indirect-heat thermal processors for heating or cooling bulk
solids may utilize hot gases for heating or drying bulk solids or cool gases
for
cooling the bulk solids as the bulk solids flow through the heater, cooler, or
dyer. The use of such gases is inefficient as large volumes of air or other
gases are utilized and waste heat in the exhaust gas is difficult to recover.
[0003] Heat transfer plates or tubes provide improved efficiency in
heat
exchangers by indirectly heating or cooling bulk solids that flow, under the
force of gravity, through a heat exchanger. The heat transfer plates or tubes
include a heat exchange fluid flowing through the plates or tubes and the bulk
solids are heated or cooled as they flow through spaces between adjacent
heat transfer plates or tubes.
[0004] Applications for such heat exchangers vary widely. The heat
transfer systems including plates or tubes referred to above are generally
useful in relatively low pressure and low temperature heat exchange
applications. Such heat exchangers are unsuitable in other applications in
which high temperature fluids or high pressure fluids are utilized due to
limitations of the heat transfer plates and tubes. For example, applications
for energy recovery and storage may involve hot bulk solids and high pressure
heat exchange fluid from which heat recovery is desirable.
[0005] Improvements to heat exchangers are desirable.
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SUMMARY
[0006] According to one aspect of an embodiment, a heat exchanger
includes an inlet for receiving bulk solids, a plurality of heat transfer
plate
assemblies, a plurality of spacers disposed between adjacent heat transfer
-- plate assemblies, and supports for supporting the plurality of heat
transfer
plate assemblies. The heat transfer plate assemblies include a first sheet
having a first pair of holes extending through the first sheet and channels
extending along a surface thereof, for the flow of fluid from a first of the
first
pair of holes, through the channels, to a second of the first pair of holes,
and
a second sheet bonded to the first sheet to enclose the channels between the
first sheet and the second sheet, the second sheet including a second pair of
holes generally aligned with the first pair of holes of the first sheet to
form
first through holes and second through holes to facilitate flow of the fluid
through the first through holes, through the channels, and through the second
through holes. The spacers are disposed between adjacent heat transfer plate
assemblies to space the adjacent heat transfer plate assemblies apart to
facilitate the flow of the bulk solids from the inlet, between the adjacent
heat
transfer plate assemblies.
[0007] According to another aspect of an embodiment, a heat exchanger
is provided. The heat exchanger includes an inlet for receiving bulk solids, a
plurality of heat transfer plate assemblies arranged in banks with the heat
transfer plate assemblies of each bank arranged generally parallel to each
other, a plurality of spacers disposed between adjacent heat transfer plate
assemblies within each bank, and supports for supporting the banks of heat
-- transfer plate assemblies. Each heat transfer plate assembly includes a
first
sheet having channels extending along a surface thereof, and a second sheet
bonded to the first sheet to enclose the channels between the first sheet and
the second sheet. The first sheet and the second sheet together have first
through holes near a first side edge of the heat transfer plate assemblies, in
fluid communication with first ends of the channels, and second through holes
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near a second side edge of the heat transfer plate assemblies, in fluid
communication with second ends of the channels to facilitate flow of the fluid
through the first through holes, through the channels, and through the second
through holes. The spacers are disposed between adjacent heat transfer plate
.. assemblies within each bank, to space the adjacent heat transfer plate
assemblies apart to facilitate the flow of the bulk solids from the inlet,
between the adjacent heat transfer plate assemblies, the spacers including
holes extending therethrough. The heat transfer plate assemblies and
spacers in each bank are coupled together such that the first through holes of
the heat transfer plate assemblies and holes of the spacers form a first
conduit, and the second through holes and spacers form a second conduit in
each bank.
[0008] According to yet another embodiment, there is provided a bank
of heat transfer plate assemblies for use in a heat exchanger. The bank of
.. heat transfer plate assemblies includes a plurality of heat transfer plate
assemblies arranged generally parallel to each other. The heat transfer plate
assemblies include a first sheet having channels extending along a surface
thereof, and a second sheet bonded to the first sheet to enclose the channels
between the first sheet and the second sheet, the first sheet and the second
sheet together having first through holes near a first side edge of the heat
transfer plate assemblies and in fluid communication with first ends of the
channels, and second through holes near a second side edge of the heat
transfer plate assemblies and in fluid communication with second ends of the
channels to facilitate flow of the fluid through the first through holes,
through
the channels, and through the second through holes. The bank also includes
a plurality of spacers disposed between adjacent heat transfer plate
assemblies to space the adjacent heat transfer plate assemblies apart to
facilitate the flow of the bulk solids between the adjacent heat transfer
plate
assemblies, the spacers including holes extending therethrough. The heat
.. transfer plate assemblies and spacers in the bank are coupled together such
that the first through holes of the heat transfer plate assemblies and holes
of
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the spacers form a first conduit, and the second through holes and spacers
form a second conduit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Embodiments of the present invention will be described, by way
of example, with reference to the drawings and to the following description,
in
which:
[0010] FIG. 1 is a perspective view of a heat exchanger in accordance
with an embodiment;
[0011] FIG. 2 is a side view of the heat exchanger of FIG. 1;
[0012] FIG. 3 is a front view of the heat exchanger of FIG. 1;
[0013] FIG. 4 is a front view of a sheet of a heat transfer plate
assembly
in accordance with an embodiment;
[0014] FIG. 5 is a view of spacers utilized between heat transfer
plate
assemblies in a bank in accordance with an embodiment;
[0015] FIG. 6 is an exploded perspective view of a bank of heat transfer
plate assemblies in accordance with an embodiment;
[0016] FIG. 7 is a perspective view of a bank of heat transfer plate
assemblies in accordance with an embodiment;
[0017] FIG. 8 is a top view of the heat exchanger of FIG. 1;
[0018] FIG. 9 is a top view of the heat exchanger of FIG. 1, with the
inlet removed;
[0019] FIG. 10 is a top view of the portion of the heat exchanger of
FIG.
9, drawn to a larger scale.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] For simplicity and clarity of illustration, reference numerals
may
be repeated among the figures to indicate corresponding or analogous
elements. Numerous details are set forth to provide an understanding of the
embodiments described herein. The embodiments may be practiced without
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these details. In other instances, well-known methods, procedures, and
components have not been described in detail to avoid obscuring the
embodiments described. The description is not to be considered as limited to
the scope of the embodiments described herein.
[0021] The disclosure generally relates to heat exchangers for heating or
cooling bulk solids, and the corresponding cooling or heating of the heat
transfer fluid. The heat exchanger includes an inlet for receiving bulk
solids, a
plurality of heat transfer plate assemblies, a plurality of spacers disposed
between adjacent heat transfer plate assemblies, and supports for supporting
the plurality of heat transfer plate assemblies. The heat transfer plate
assemblies include a first sheet having a first pair of holes extending
through
the first sheet and channels extending along a surface thereof, for the flow
of
fluid from a first of the first pair of holes, through the channels, to a
second of
the first pair of holes, and a second sheet bonded to the first sheet to
enclose
the channels between the first sheet and the second sheet, the second sheet
including a second pair of holes generally aligned with the first pair of
holes of
the first sheet to form first through holes and second through holes to
facilitate flow of the fluid through the first through holes, through the
channels, and through the second through holes. The spacers are disposed
between adjacent heat transfer plate assemblies to space the adjacent heat
transfer plate assemblies apart to facilitate the flow of the bulk solids from
the
inlet, between the adjacent heat transfer plate assemblies.
[0022] FIG. 1 through FIG. 3 show views of an embodiment of a heat
exchanger 100, which in this example is utilized for cooling bulk solids. The
heat exchanger 100 includes an inlet 102 in a top of an inlet housing 104 at
the top of the heat exchanger 100, for introducing bulk solids into the heat
exchanger 100. The bulk solids may be any suitable flowable solids such as
ceramic beads, sand, sintered bauxite, or any other suitable flowable solid.
The inlet housing 104 provides an inlet hopper 106. The inlet hopper 106
facilitates distribution of bulk solids that flow from the inlet 102, as a
result of
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the force of gravity by disbursing the bulk solids over substantially the
whole
cross-section of the heat exchanger 100.
[0023] The heat transfer plate assemblies are arranged in rows. In the
present example, the heat transfer plate assemblies 108 are arranged in eight
rows, referred to as banks 110, 112, 114, 116, 118, 120, 122, 124, each
including a plurality of the heat transfer plate assemblies 108. The heat
transfer plate assemblies 108 in the first bank 110 are generally parallel to
each other and are spaced apart to leave passageways between adjacent heat
transfer plate assemblies 108 for the flow of bulk solids. Similarly, the heat
transfer plate assemblies 108 of the subsequent banks 112, 114, 116, 118,
120, 122, 124 are generally parallel to each other and are spaced apart to
leave passageways between the adjacent heat transfer plate assemblies 108
of each of the banks for the flow of bulk solids.
[0024] The banks 110, 112, 114, 116, 118, 120, 122, 124 are arranged
generally vertically with the first bank 110 at the top, followed by the
second
bank 112, the third bank 114, the fourth bank 116, the fifth bank 118, the
sixth bank 120, the seventh bank 122, and the eight, or bottom bank 124.
[0025] The banks 110, 112, 114, 116, 118, 120, 122, 124 are supported
on support rails 126 that extend under the bottom bank 124 of heat transfer
plate assemblies 108. Further support rails may also be utilized, for example,
between banks. Alternatively or in addition, supports may extend above one
or more banks for supporting the banks from above. Although the heat
exchanger 100 of FIG. 1 includes eight banks 110, 112, 114, 116, 118, 120,
122, 124 of heat transfer plate assemblies 108, other suitable numbers heat
transfer plate assemblies 108 may be utilized and any suitable number of heat
transfer plate assemblies 108 may be utilized in each bank.
[0026] The bulk solids flow through the spaces between the heat
transfer plate assemblies 108, which spaces provide the passageways through
the banks 110, 112, 114, 116, 118, 120, 122, 124 of the heat transfer plate
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assemblies 108. The bulk solids that contact the heat transfer plate
assemblies 108 are deflected into the passageways.
[0027] The bulk solids then flow from the passageways and are
discharged, for example, through a discharge hopper 148 in which the bulk
solids are discharged under a "choked" flow to control the rate of flow
through
the heat exchanger 100, and out of the heat exchanger 100. In the example
shown in FIG. 1, the discharge hopper 148 is a cone hopper. Other discharge
devices and geometries may be successfully implemented, however.
[0028] Reference is now made to FIG. 4, which shows a front view of a
portion of a heat transfer plate assembly 108. A heat transfer plate assembly
108 of the heat exchanger 100 includes at least two thin sheets 402 of, for
example, an alloy such as Inconel, a stainless steel, or any other suitable
alloy. In the present example, the heat transfer plate assembly 108 includes
four thin sheets of about 0.060 inches in thickness (1.524mm). The sheets in
the present embodiment are generally rectangular, including long edges 404
and shorter side edges 406. The sheets 402 may be any suitable shape and
size, however. In the present example, the long edges 404 are about 26
inches (66.0 cm) and the short edges are about 8 inches (20.3 cm) long.
[0029] Each of the sheets include a pair of holes 408, 410 extending
through the thickness of the sheets, with a first one of the holes 408 near a
first side edge 406 and the second hole 410 near the opposing side edge 406.
[0030] Three of the sheets 402 include channels 412 therein. The
channels 412 may be selectively etched in each sheet, for example, by
photoetching to create channels 412 in a face of the sheet 402, with the
channels 412 extending continuously from the first hole 408 to the second
hole 410. The channels 412 do not extend through the entire thickness of the
sheet 402. The channels 412 are spaced from each other and are distributed
between the long edges 404 of the sheet. In the present example, 13
channels 412 are shown extending from the first hole 408 to the second hole
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410. Any suitable number of channels 412 may be successfully employed,
however. As indicated, the channels 412 may be formed by selectively
photoetching the sheets 402. The resulting channels 412 are generally half-
circular in cross section as a result of the selective etching process.
[0031] The four sheets 402 that together make up the heat transfer
plate assembly 108, are stacked together such that each face 414 that
includes the channels 412, abuts an adjacent sheet 402 to enclose the
channels between sheets 402. The stack of sheets 402 is heated in a vacuum
furnace with mechanical pressure applied, to cause diffusion of the sheets 402
into each other. The diffusion results in a single heat transfer plate
assembly
of about 0.240 inches thickness (6.096mm) that includes the stacked sheets
402 that are diffusion bonded together.
[0032] In the example shown in FIG. 4, the channels 412 extend across
the sheet 402 from the first hole 408 to the second hole 410. Each channel
412 extends across the sheet 402 once. Alternatively, each channel may
extend across the sheet more than once, such that each channel extends from
the first hole, and across the sheet 402 in multiple passes before joining the
second hole. The second hole may optionally be on a same side of the sheets
such that both holes are near the same side edge 406 and each channel
.. extends across the sheet 402 in an even number of passes from the first
hole
to the second hole. Optionally, the channels may include portions that extend
generally vertically or the channels, and thus the heat transfer plate
assemblies may be configured such that the channels flow substantially
vertically.
[0033] Diffusion bonding may be carried out on several stacks of sheets
402 to create several diffusion bonded plates at a time. The diffusion bonded
plates may be maintained separate by including a sheet or plate of dissimilar
material that does not diffusion bond with the material of the sheets 402,
between each stack of the sheets 402 that form a single heat transfer plate
assembly 108.
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[0034] In the above description, each sheet 402 is described as
including the first hole 408 and the second hole 410. Alternatively, the
sheets
may be selectively etched as described and diffusion bonded prior to creating
the holes through the resulting heat transfer plate assembly 108.
[0035] Referring to FIG. 5, spacers 502 are shown. The spacers 502 are
utilized to space the heat transfer plate assemblies 108 apart in the heat
exchanger 100, to facilitate the flow of bulk solids between the heat transfer
plate assemblies 108. The spacers 502 are generally rectangular in the
present example, and each spacer 502 includes a hole 504 extending
therethrough. For the purpose of the present example, a side edge 506 of the
spacers 502 is about the length of a side edge 406 of the sheets 402. The top
and bottom edges 508 of the spacers 502, however, have a length that is
significantly shorter than the long edges 404 of the sheets 402. The holes 504
extending through the spacers are similar in size to the holes in the sheets
402. The spacers 502 may be any suitable thickness to provide suitable
spacing between the heat transfer plate assemblies 108 for the flow of bulk
solids between the heat transfer plate assemblies 108. For example, the
spacers 502 may be about 0.25 inches (6.35 mm) thick.
[0036] The heat transfer plate assemblies 108 are stacked with two
-- spacers 502 disposed between each pair of adjacent heat transfer plate
assemblies 108, as illustrated in FIG. 6. A side edge 506 of each of the two
spacers 502 is adjacent a respective side edge 406 of each adjacent heat
transfer plate assembly 108, thus providing a space, equal to the thickness of
the spacers 502, between center portions of adjacent heat transfer plate
assemblies 108. The heat transfer plate assemblies 108 and spacers 502 are
joined together to provide a single bank of the heat transfer plate assemblies
108. The heat transfer plate assemblies 108 and the spacers 502 are aligned
such that the holes 504 in the spacers 502 are aligned with the holes 408,
410 in the sheets.
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[0037] As illustrated in FIG. 7, end plates 702 are also stacked with
the
heat transfer plate assemblies 108 such that each bank of heat transfer plate
assemblies 108 includes two end plates 702, with one on each end of the
stack. As with the sheets 402, each end plate 702 is generally rectangular in
shape and includes side edges 704 that are about the length of the side edges
406 of the sheets 402 and long edges 706 that are about the length of the
long edges 404 of the sheets. The end plates 702 may be made of any
suitable material, such as Inconel or other suitable alloy. The end plates 702
are spaced from the adjacent heat transfer plate assembly 108 by spacers
502 and the end plates 702 are also joined in the stack, to the adjacent
spacers 502. The end plates 702 include nozzles 708 that align with the holes
504 in the spacers 502 and with the holes 408, 410 in the sheets 402.
[0038] The end plates 702, spacers 502, and heat transfer plate
assemblies 108 may all be joined together in the stack by diffusion bonding,
by heating in a vacuum and under mechanical pressure. Thus, the end plates
702, the spacers 502, and the heat transfer plate assemblies 108 are joined
together to form a single, unitary bank of heat transfer plate assemblies.
Alternatively, the end plates 702, the heat transfer plate assemblies 108, and
the spacers 502 may be bonded together by brazing or utilizing any other
suitable bonding technique.
[0039] When joined to provide the unitary bank, the nozzles 708 of the
end plates 702 are in fluid communication with the holes 504 in the spacers
502 and with the holes 408, 410 in the sheets 402 that form the heat transfer
plate assemblies 108. Thus, the through holes of the heat transfer plate
assemblies 108 in the first bank are all in fluid communication by the spacers
to form a continuous conduit, utilized as a fluid manifold through the heat
transfer plate assemblies 108 and spacers 502. Two continuous fluid
manifolds are thus formed through the heat transfer plate assemblies 108 and
the spacers 502 in the unitary bank.
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[0040] The nozzles 708 may be utilized as a fluid inlet and a fluid
outlet
to facilitate the flow of fluid into one of the fluid manifolds formed in the
heat
transfer plate assemblies 108 and the spacers 502, through the channels in
the sheets 402 that form the heat transfer plate assemblies 108, and out
through the other fluid manifold formed in the heat transfer plate assemblies
108. Thus, two integral fluid manifolds are formed in the bank of heat
transfer plate assemblies 108, for use as an inlet manifold and an outlet
manifold.
[0041] A plurality of banks are joined together in a stack as
illustrated in
FIG. 1 through FIG. 3. As described, the present example includes eight
banks 110, 112, 114, 116, 118, 120, 122, 124 arranged generally vertically
with the first bank 110 at the top, followed by the second bank 112, the third
bank 114, the fourth bank 116, the fifth bank 118, the sixth bank 120, the
seventh bank 122, and the eight, or bottom bank 124.
[0042] Referring now to FIG. 8, the inlet housing 104, which has a
generally a rectangular cross-section, is coupled to the top bank 110 of the
heat transfer plate assemblies 108. The inlet housing 104 provides the inlet
hopper 106 for facilitating distribution of bulk solids that flow from the
inlet
102, as a result of the force of gravity. Thus, the bulk solids are disbursed
over substantially the whole cross-section of the heat exchanger 100.
[0043] Referring to FIG. 9 and FIG. 10, the heat transfer plate
assemblies 108, and end plates 702 are illustrated. Support ribs 1002 extend
generally vertically between and abutting adjacent heat transfer plate
assemblies 108. The support ribs 1002 are included to stabilize the heat
.. transfer plate assemblies 108 over the length of the heat transfer plate
assemblies 108. The support ribs 1002 are included to reduce the deflection
of the heat transfer plate assemblies 108 when in use. As shown, the heat
transfer plate assemblies 108 are closely spaced and are disposed generally
vertically to facilitate the flow of the bulk solids, by the force of gravity,
through the spaces between the heat transfer plate assemblies of each bank,
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and to the outlet 150. Thus, the spaces between the heat transfer plate
assemblies 108 in each of the banks 110, 112, 114, 116, 118, 120, 122, 124
provide passageways for the flow of bulk solids through the heat exchanger
100.
[0044] Referring again to FIG. 1 through FIG. 3, the discharge hopper
148 in the present example is a generally cone-shaped housing coupled to the
bottom bank 124 via the support rails 126 on which the banks 110, 112, 114,
116, 118, 120, 122, 124 are supported. The cone-shaped housing is utilized
to establish generally uniform bulk solids mass flow through the heat
exchanger 100. The cone-shaped housing provides a "choked flow" of bulk
solids exiting the heat exchanger 100, to control the flow rate of the bulk
solids through the heat exchanger.
[0045] The bottom bank 124 includes an inlet flange 130 attached to a
nozzle 708 of an end plate on a first side 132 of the heat exchanger 100,
which nozzle 708 is utilized as the fluid inlet to the inlet manifold formed
in
the heat transfer plate assemblies 108 and spacers 502. A heat exchange
fluid source is coupled to the inlet flange 130 when the heat exchanger 100 is
in use, for supplying a heat exchange fluid, such as supercritical carbon
dioxide, to the heat exchanger 100. The nozzle 708 that is coupled to the end
plate on an opposing side, referred to as the second side 134, and is in fluid
communication with the outlet manifold formed in the bottom bank 124, is
fluidly coupled by a fluid line 136 to the nozzle 708 that is coupled to the
inlet
manifold formed in the seventh bank 122. Thus, the fluid line 136 couples the
fluid outlet manifold of the bottom bank 124 to the fluid inlet manifold of
the
bank above (the seventh bank 122). A fluid line 138 coupled to the nozzle
708 on the first side 132 of the heat exchanger 100 that is in fluid
communication with the fluid outlet manifold of the seventh bank 122 is
coupled to the nozzle 708 that is in fluid communication with the inlet
manifold of the sixth bank 120. The coupling of fluid outlet manifolds to
fluid
inlet manifolds of the bank above continues such that the fluid flows in a
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serpentine fashion through the heat exchanger, to the top bank 110. Thus,
the inlet manifold of each of the top, second, third, fourth, fifth, sixth,
and
seventh banks 110, 112, 114, 116, 118, 120, 122 is coupled to the fluid
outlet manifold of the respective bank below. The remaining nozzles 708 that
are not utilized for coupling an inlet flange 130, an outlet flange 140, or a
fluid
line such as the fluid lines 136, 138, are plugged to substantially seal the
nozzles and thereby inhibit the flow of the heat exchange fluid out of these
unutilized nozzles 708.
[0046] The top bank 110 includes an outlet flange 140 attached to a
nozzle 708 on an end plate on a first side 132 of the heat exchanger for
coupling an outlet line thereto for the flow of the heat exchange fluid, after
passing through the heat transfer plate assemblies 108 and out of the heat
exchanger 100. In the present example, 8 banks are utilized and the outlet
flange 140 is attached to the nozzle 708 on the end plate on the first side
132
of the heat exchanger. Alternatively, an outlet flange may be attached to a
nozzle on an end plate on the second side 134 when there are an odd number
of banks of heat transfer plate assemblies 108.
[0047] Thus, the heat exchange fluid is utilized for indirect heat
exchange with the bulk solids as the heat exchange fluid heats the heat
transfer plate assemblies 108 for the transfer of heat to the bulk solids as
the
bulk solids flow through the heat exchanger 100. The heat exchange fluid,
however, is separate from and not in contact with the bulk solids that are
heated or cooled in the heat exchanger 100. The heat exchange fluid may be
introduced to the heat transfer plate assemblies 108 at high temperature and
pressure, for example, utilizing supercritical CO2 at a pressure of 200 bar.
[0048] The heat transfer plate assemblies 108 of one bank may be
offset from the heat transfer plate assemblies of an adjacent bank in any
suitable manner. For example, an end plate 702 on one side of a bank may
be thicker than the end plate 702 on the opposing side of the bank. The
banks may be assembled such that the thicker end plate 702 is one side for a
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first bank and is on an opposing side for the adjacent bank. Thus, the thicker
end plate 702 is located on alternate sides. Utilizing this assembly including
banks with the thicker end plates located on alternating sides, the heat
transfer plate assemblies 108 may be laterally offset such that the heat
transfer plate assemblies 108 of the banks are not all vertically aligned,
facilitating heating or cooling of the bulk solids. The resulting dimensions
of
each bank are such that the banks are similar in size and thus, the outer
surfaces of the end plates 702 of one bank are vertically aligned with the
outer surfaces of the end plates 702 of a subsequent bank.
[0049] End plates 702 of different thicknesses on alternating sides is one
example of a suitable assembly for achieving an offset in the heat transfer
plate assemblies 108 from bank to bank. Such an offset may be realized
utilizing any other suitable assembly such that the heat transfer plate
assemblies 108 of one bank 110, 112, 114, 116, 118, 120, 122 are not
vertically aligned with the heat transfer plate assemblies 108 of a vertically
adjacent bank 110, 112, 114, 116, 118, 120, 122 while maintaining similar
outer dimensions of the banks 110, 112, 114, 116, 118, 120, 122.
[0050] Each bank 110, 112, 114, 116, 118, 120, 122 of heat transfer
plate assemblies 108 is sealed by the end plates 702 and the spacers 502
that, for example, are diffusion bonded together. The banks 110, 112, 114,
116, 118, 120, 122 may be joined together in a stack, and a seal, such as a
gasket disposed between vertically adjacent banks 110, 112, 114, 116, 118,
120, 122, for example, to inhibit both dust and air from escaping from the
heat exchanger 100. The use of such gaskets may be advantageous when a
pressure differential exists between the interior of the heat exchanger 100
and outside the heat exchanger 100 or when a sweep gas is utilized.
Alternatively, the banks 110, 112, 114, 116, 118, 120, 122 may be joined
together in a stack in the heat exchanger 100 without additional seals such
that surfaces of vertically adjacent banks 110, 112, 114, 116, 118, 120, 122
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of heat transfer plate assemblies abut each other to inhibit escape of
particles
out of the heat exchanger 100.
[0051] The operation of the heat exchanger 100 will now be described
with reference to FIG. 1 through FIG. 3. When bulk solids are fed into the
heat exchanger 100, through the inlet 102, the bulk solids flow downwardly as
a result of the force of gravity from the inlet 102, into and through spaces
between the heat transfer plate assemblies 108. The bulk solids that contact
the heat transfer plate assemblies 108 are generally deflected into the spaces
between the heat transfer plate assemblies. As the bulk solids flow between
the heat transfer plate assemblies 108, the bulk solids are heated or cooled,
depending on the application. The heat exchange fluid that flows through the
heat transfer plate assemblies indirectly heats the bulk solids.
[0052] The bulk solids then flow through out of the discharge hopper
148, which controls the flow of bulk solids from the heat exchanger 100, and
out the outlet 150 through which the heated or cooled bulk solids are
discharged from the heat exchanger 100.
[0053] In the above description, the sheets 402 are etched and
diffusion
bonded together to form the heat transfer plate assemblies 108. Rather than
etching, followed by diffusion bonding, the heat transfer plate assemblies 108
may be 3D printed and then bonded together. Alternatively, the channels 412
may be machined or laser cut into the sheets 402 prior to assembly. The heat
transfer plate assemblies may be brazed together rather than diffusion
bonded.
[0054] As described above, the heat transfer plate assemblies 108, the
-- spacers 502, and the end plates 702 are coupled together by, for example,
diffusion bonding. Alternatively, the heat transfer plate assemblies 108, the
spacers 502, and the end plates 702 may be coupled together by tie rods that
extend through the entire bank to align and maintain the heat transfer plate
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assemblies 108, the spacers 502, and the end plates 702 in the bank. The
entire bank may be sealed or brazed.
[0055] In addition, the heat transfer plate assemblies 108 are
described
as formed from four sheets. Any other suitable number of sheets may be
utilized to form the heat transfer plate assemblies 108. For example, two or
more sheets may be utilized to form the heat transfer plate assemblies.
[0056] In the above-described examples, the through holes of the heat
transfer plate assemblies 108 and the spacers in the first bank are all in
fluid
communication to form continuous conduits, utilized as fluid manifolds. The
two continuous fluid manifolds are thus formed through the heat transfer
plate assemblies 108 and the spacers 502 in the unitary bank. Alternatively,
spacers or sheets within the heat transfer plate assemblies may include only a
single hole such that heat exchange fluid travels from the inlet manifold,
through more than one heat transfer plate assembly or more than one sheet,
before travelling to the outlet manifold.
[0057] Advantageously, the heat transfer plate assemblies 108 and the
spacers 502 form integral manifolds within the banks. A very high number of
relatively thin heat transfer plate assemblies 108 may be employed without
requiring a separate manifold coupled to each heat transfer plate assembly
108. High temperature and high pressure heat exchange fluid may be utilized
for indirect heat exchange with the bulk solids.
[0058] The described embodiments are to be considered in all respects
only as illustrative and not restrictive. The scope of the claims should not
be
limited by the preferred embodiments set forth in the examples, but should be
given the broadest interpretation consistent with the description as a whole.
All changes that come with meaning and range of equivalency of the claims
are to be embraced within their scope.
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